How to grow vegetables year-round

Do you dread surrendering your vegetable plot to Old Man Winter? You don't have to, says Eliot Coleman, author of Four Season Harvest and The Winter Harvest Handbook. Be the four-season gardener. Here are his tips.

Add protection

For cold-hardy crops, fashion a tunnel-style greenhouse out of electrical conduit covered with plastic sheeting. Seed catalogues sell "hoop benders," which form the conduit into a horseshoe shape that you then attach to a four-sided wooden frame. "If you and your neighbours go in on the tool together, you can make a mini-greenhouse for almost no money at all," says Mr. Coleman, who tends an experimental market garden at Four Season Farm in Harborside, Me., with his wife, author and Washington Post columnist Barbara Damrosch.

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Change the climate

Winter crops will thrive inside an old-fashioned cold frame - a bottomless box with a glass top that you can build (old windows work well) or purchase readymade. "Basically, you've changed the climate," Mr. Coleman explains. "You've moved your garden 500 miles [800 kilometres] or one and a half growing zones, south. This lets you harvest up to Christmas with the very hardiest greens." He suggests starting with spinach and Asian vegetables such as bok choy.

Double up

As temperatures drop, or if your region is already pretty chilly, you can add a greenhouse around your cold frame. "With a cold frame you're providing a sweater for your plants. The greenhouse is like a windbreaker over the sweater," Mr. Coleman says. "That second layer moves you an additional 500 miles south."

Sow now, reap later

Unless you live in a relatively balmy climate such as Vancouver's, winter crops should be sown by mid-October. But you can kick off an early-spring harvest by planting inside a cold frame in late fall. "Put some seeds in, no matter what," Mr. Coleman advises. "Even if you get nothing to eat until spring, you'll learn a lot. Gardening is a learning game."

Keep plants young

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If your seeds were sown on the late side, use seedlings to experiment with harvesting this winter. "Young plants are a lot stronger than old plants in the cold," Mr. Coleman says. "Baby leaves can freeze every night and thaw every day and still look beautiful."

Keep greens young by trimming the outer leaves so the inner leaves can keep developing. "It's a perpetual salad," Mr. Coleman says, adding that the best time to harvest is the middle of the day when plants have defrosted.

Move indoors

Sprouts and herbs may fare well on a sunny windowsill, but most houses are too warm to grow other crops with natural light. "In the cold, the plant will grow slowly because the temperature is low," Mr. Coleman explains, "and slow growth is all the winter light can give them."

A better option would be fluorescent grow lights. Fruit-bearing crops such as peppers will need at least 12 hours of light each day, plus regular watering and misting to counteract dry indoor air. Choose small varieties suited to container gardening.

Special to The Globe and Mail

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And don't do this … shelter plants in more than two layers of protection. You'll cut out too much light.

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